Numerical simulation of meso-damage and failure process of concrete with defects

The concrete was regarded as a kind of four-phase composite material consisting of aggregate,mortar,interfacial transition and random micro-defects.The defects were characterized as circular pores and penny cracks.The stresscrack width model was employed to depict the nonlinear constitutive relationship among the aggregate,mortar and interfacial transition.The stress-strain curves of specimens during failure process under uniaxial tensile load as well as the load-displacement curves under bending tension were obtained.The influences of the circular pores and penny cracks as well as their contents on the failure process and the ultimate load of concrete were analyzed.The results show that the ultimate load of concrete specimens with circular aggregate is larger than that with arbitrary polygon aggregate.The defects can weaken the macro-mechanical properties of concrete.The penny cracks are more disadvantageous than the circular pores.